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	$10.76	5.232%	$11.323	$11.32	$11.30	$11.30
Purchase #2	$56.66	5.440%	$59.7423	$59.74	$59.75	$59.70
Purchase #3	$101.68	10.201%	$112.0524	$112.05	$112.05	$112.10
Purchase #4	$243.72	7.566%	$262.1599	$262.16	$262.15	$262.20
Purchase #5	$122.76	7.303%	$131.7252	$131.73	$131.75	$131.70
Purchase #6	$248.71	6.229%	$264.2021	$264.20	$264.20	$264.20
Purchase #7	$168.76	13.385%	$191.3485	$191.35	$191.35	$191.30
7 purchase totals =	$953.05		$1,032.5534	$1,032.55	$1,032.55	$1,032.50