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	$44.89	5.377%	$47.3037	$47.30	$47.30	$47.30
Purchase #2	$97.27	4.842%	$101.9798	$101.98	$102.00	$102.00
Purchase #3	$80.61	6.202%	$85.6094	$85.61	$85.60	$85.60
Purchase #4	$124.72	4.347%	$130.1416	$130.14	$130.15	$130.10
Purchase #5	$67.41	6.193%	$71.5847	$71.58	$71.60	$71.60
Purchase #6	$136.75	13.385%	$155.054	$155.05	$155.05	$155.10
Purchase #7	$73.98	11.851%	$82.7474	$82.75	$82.75	$82.70
7 purchase totals =	$625.63		$674.4206	$674.41	$674.45	$674.40