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	$183.96	7.173%	$197.1555	$197.16	$197.15	$197.20
Purchase #2	$88.51	13.396%	$100.3668	$100.37	$100.35	$100.40
Purchase #3	$55.31	6.643%	$58.9842	$58.98	$59.00	$59.00
Purchase #4	$211.84	5.216%	$222.8896	$222.89	$222.90	$222.90
Purchase #5	$35.92	5.457%	$37.8802	$37.88	$37.90	$37.90
Purchase #6	$161.25	4.552%	$168.5901	$168.59	$168.60	$168.60
Purchase #7	$216.47	9.507%	$237.0498	$237.05	$237.05	$237.00
7 purchase totals =	$953.26		$1,022.9162	$1,022.92	$1,022.95	$1,023.00