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	$72.57	3.394%	$75.033	$75.03	$75.05	$75.00
Purchase #2	$72.79	8.300%	$78.8316	$78.83	$78.85	$78.80
Purchase #3	$100.28	11.540%	$111.8523	$111.85	$111.85	$111.90
Purchase #4	$209.42	9.819%	$229.9829	$229.98	$230.00	$230.00
Purchase #5	$136.90	13.835%	$155.8401	$155.84	$155.85	$155.80
Purchase #6	$20.91	6.268%	$22.2206	$22.22	$22.20	$22.20
Purchase #7	$223.96	7.501%	$240.7592	$240.76	$240.75	$240.80
7 purchase totals =	$836.83		$914.5197	$914.51	$914.55	$914.50