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	$147.99	3.426%	$153.0601	$153.06	$153.05	$153.10
Purchase #2	$162.87	3.112%	$167.9385	$167.94	$167.95	$167.90
Purchase #3	$183.78	6.813%	$196.3009	$196.30	$196.30	$196.30
Purchase #4	$97.96	3.132%	$101.0281	$101.03	$101.05	$101.00
Purchase #5	$87.61	3.527%	$90.7	$90.70	$90.70	$90.70
Purchase #6	$170.90	12.732%	$192.659	$192.66	$192.65	$192.70
Purchase #7	$243.61	12.437%	$273.9078	$273.91	$273.90	$273.90
7 purchase totals =	$1,094.72		$1,175.5944	$1,175.60	$1,175.60	$1,175.60