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	$162.52	11.651%	$181.4552	$181.46	$181.45	$181.50
Purchase #2	$130.32	8.391%	$141.2552	$141.26	$141.25	$141.30
Purchase #3	$45.58	13.530%	$51.747	$51.75	$51.75	$51.70
Purchase #4	$147.99	6.817%	$158.0785	$158.08	$158.10	$158.10
Purchase #5	$214.74	4.186%	$223.729	$223.73	$223.75	$223.70
Purchase #6	$145.66	4.858%	$152.7362	$152.74	$152.75	$152.70
Purchase #7	$98.46	4.498%	$102.8887	$102.89	$102.90	$102.90
7 purchase totals =	$945.27		$1,011.8898	$1,011.91	$1,011.95	$1,011.90