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	$175.39	11.185%	$195.0074	$195.01	$195.00	$195.00
Purchase #2	$27.48	11.820%	$30.7281	$30.73	$30.75	$30.70
Purchase #3	$99.34	9.837%	$109.1121	$109.11	$109.10	$109.10
Purchase #4	$205.26	6.475%	$218.5506	$218.55	$218.55	$218.60
Purchase #5	$170.98	8.731%	$185.9083	$185.91	$185.90	$185.90
Purchase #6	$43.41	4.400%	$45.32	$45.32	$45.30	$45.30
Purchase #7	$204.59	6.596%	$218.0848	$218.08	$218.10	$218.10
7 purchase totals =	$926.45		$1,002.7113	$1,002.71	$1,002.70	$1,002.70