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	$167.66	10.850%	$185.8511	$185.85	$185.85	$185.90
Purchase #2	$99.56	11.218%	$110.7286	$110.73	$110.75	$110.70
Purchase #3	$14.71	11.440%	$16.3928	$16.39	$16.40	$16.40
Purchase #4	$227.99	11.530%	$254.2772	$254.28	$254.30	$254.30
Purchase #5	$157.58	10.459%	$174.0613	$174.06	$174.05	$174.10
Purchase #6	$73.69	11.483%	$82.1518	$82.15	$82.15	$82.20
Purchase #7	$165.81	7.763%	$178.6818	$178.68	$178.70	$178.70
7 purchase totals =	$907.00		$1,002.1446	$1,002.14	$1,002.20	$1,002.30