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	$186.41	7.795%	$200.9407	$200.94	$200.95	$200.90
Purchase #2	$87.43	3.482%	$90.4743	$90.47	$90.45	$90.50
Purchase #3	$53.88	3.460%	$55.7442	$55.74	$55.75	$55.70
Purchase #4	$59.32	3.123%	$61.1726	$61.17	$61.15	$61.20
Purchase #5	$209.74	4.647%	$219.4866	$219.49	$219.50	$219.50
Purchase #6	$206.69	7.376%	$221.9355	$221.94	$221.95	$221.90
Purchase #7	$205.78	9.225%	$224.7632	$224.76	$224.75	$224.80
7 purchase totals =	$1,009.25		$1,074.5171	$1,074.51	$1,074.50	$1,074.50