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	$41.81	10.488%	$46.195	$46.20	$46.20	$46.20
Purchase #2	$102.43	8.481%	$111.1171	$111.12	$111.10	$111.10
Purchase #3	$202.89	11.461%	$226.1432	$226.14	$226.15	$226.10
Purchase #4	$156.53	6.723%	$167.0535	$167.05	$167.05	$167.10
Purchase #5	$130.25	13.235%	$147.4886	$147.49	$147.50	$147.50
Purchase #6	$140.52	5.695%	$148.5226	$148.52	$148.50	$148.50
Purchase #7	$240.40	10.133%	$264.7597	$264.76	$264.75	$264.80
7 purchase totals =	$1,014.83		$1,111.2797	$1,111.28	$1,111.25	$1,111.30