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	$131.93	11.430%	$147.0096	$147.01	$147.00	$147.00
Purchase #2	$182.27	7.543%	$196.0186	$196.02	$196.00	$196.00
Purchase #3	$209.91	11.849%	$234.7822	$234.78	$234.80	$234.80
Purchase #4	$12.82	3.552%	$13.2754	$13.28	$13.30	$13.30
Purchase #5	$32.78	7.623%	$35.2788	$35.28	$35.30	$35.30
Purchase #6	$126.39	3.697%	$131.0626	$131.06	$131.05	$131.10
Purchase #7	$241.72	11.138%	$268.6428	$268.64	$268.65	$268.60
7 purchase totals =	$937.82		$1,026.0700	$1,026.07	$1,026.10	$1,026.10