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	$90.54	5.731%	$95.7288	$95.73	$95.75	$95.70
Purchase #2	$192.51	9.771%	$211.3202	$211.32	$211.30	$211.30
Purchase #3	$28.71	7.603%	$30.8928	$30.89	$30.90	$30.90
Purchase #4	$196.29	13.119%	$222.0413	$222.04	$222.05	$222.00
Purchase #5	$67.59	5.589%	$71.3676	$71.37	$71.35	$71.40
Purchase #6	$163.92	11.177%	$182.2413	$182.24	$182.25	$182.20
Purchase #7	$89.70	12.265%	$100.7017	$100.70	$100.70	$100.70
7 purchase totals =	$829.26		$914.2937	$914.29	$914.30	$914.20