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	$192.82	11.585%	$215.1582	$215.16	$215.15	$215.20
Purchase #2	$171.96	11.305%	$191.4001	$191.40	$191.40	$191.40
Purchase #3	$76.28	13.392%	$86.4954	$86.50	$86.50	$86.50
Purchase #4	$64.55	3.208%	$66.6208	$66.62	$66.60	$66.60
Purchase #5	$100.54	9.293%	$109.8832	$109.88	$109.90	$109.90
Purchase #6	$170.41	7.197%	$182.6744	$182.67	$182.65	$182.70
Purchase #7	$176.62	5.381%	$186.1239	$186.12	$186.10	$186.10
7 purchase totals =	$953.18		$1,038.3560	$1,038.35	$1,038.30	$1,038.40