Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$163.47	13.494%	$185.5286	$185.53	$185.55	$185.50
Purchase #2	$242.53	12.654%	$273.2197	$273.22	$273.20	$273.20
Purchase #3	$35.59	5.478%	$37.5396	$37.54	$37.55	$37.50
Purchase #4	$128.31	12.644%	$144.5335	$144.53	$144.55	$144.50
Purchase #5	$176.88	5.701%	$186.9639	$186.96	$186.95	$187.00
Purchase #6	$129.33	13.865%	$147.2616	$147.26	$147.25	$147.30
Purchase #7	$182.89	13.352%	$207.3095	$207.31	$207.30	$207.30
7 purchase totals =	$1,059.00		$1,182.3564	$1,182.35	$1,182.35	$1,182.30