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	$167.36	4.405%	$174.7322	$174.73	$174.75	$174.70
Purchase #2	$104.67	6.148%	$111.1051	$111.11	$111.10	$111.10
Purchase #3	$199.49	4.436%	$208.3394	$208.34	$208.35	$208.30
Purchase #4	$51.83	11.784%	$57.9376	$57.94	$57.95	$57.90
Purchase #5	$166.74	6.767%	$178.0233	$178.02	$178.00	$178.00
Purchase #6	$175.48	12.197%	$196.8833	$196.88	$196.90	$196.90
Purchase #7	$82.61	11.540%	$92.1432	$92.14	$92.15	$92.10
7 purchase totals =	$948.18		$1,019.1641	$1,019.16	$1,019.20	$1,019.00